1. Field of the Invention
The present invention relates to a method of manufacturing a hard coat film, a hard coat film, a polarizing plate, and a liquid crystal display device.
2. Description of the Related Art
In an image display device, such as a cathode ray tube (CRT) display, a plasma display panel (PDP), an electroluminescence display (ELD), a vacuum fluorescent display (VFD), a field emission display (FED) or a liquid crystal display (LCD), it is appropriate to provide a hard coat film having a hard coat layer on a transparent support to prevent the display surface of the device from suffering damage.
Since a hard coat film is applied to the outermost surface of a display, it is required to have a high degree of hardness. Meanwhile, an image display device is becoming thinner and thus there has been a strong need for a thinner hard coat film.
To make a thinner hard coat film, it is also necessary to make a thinner transparent support as well. However, a thinner transparent support resulted in the reduction of the hardness of the film or was unable to tolerate the cure shrinkage in a hard coat layer and thus worse the wrinkling or curling of the film, thereby making it difficult to handle the hard coat film during the process of manufacturing or processing the hard coat film or causing a crack in the film in the process of handling, or peeling-off after adhesion. Also, a thinner transparent support increases water vapor permeability, which in turn deteriorates the moisture and heat resistance of a polarizing plate. In order to resolve these problems, inventions that use an epoxy-based compound (see Japanese Patent Application Laid-Open No. 2007-237483 and Japanese Patent Application Laid-Open No. Hei 8-073771) have been suggested.
Japanese Patent Application Laid-Open No. Hei 4-236211 discloses an example wherein a compound having an alicyclic epoxy group and a (meth)acrylate group in a molecule as an overcoat for an optical disk to suppress an inverse warpage.
A hard coat film is also given a ultra-violet ray cutting function (ultra-violet ray blocking function) for purposes of preventing a display device or the like from deteriorating due to ultra-violet rays. To date, it has been commonly practiced to impart the ultra-violet ray cutting function to a transparent support. However, making a thinner transparent support has also deteriorated its ultra-violet ray blocking function and thus a hard coat layer has also been required to have an ultra-violate ray cutting function. Herein, although an ultra-violet curable resin is used for forming a hard coat layer, the ultra-violet ray cutting function of the hard coat layer cuts the ultra-violet rays necessary for curing the hard coat layer as well, thereby deteriorating the hardness of the hard coat layer. In this regard, Japanese Patent Application Laid-Open No. 2013-204001 discloses using a specific UV absorber to improve the hardness and curling.